On March 29 Secretary of the Interior Ryan Zinke signed an order to end the Obama administration’s 2016 moratorium on new leases to mine coal on federal lands. The order also killed an ongoing analysis of the program’s impacts on the environment, particularly how the carbon dioxide created by burning that coal would hinder U.S. efforts to blunt the worst impacts of climate change.

The Trump administration has positioned lifting the coal program moratorium, along with other actions to unravel Obama-era climate action policies, as keys to restoring jobs for coal miners and prosperity to their communities. But coal was facing existential challenges long before Obama. Here’s your by-the-numbers overview of coal in the United States.

It’s hard to estimate, but there may be 3.9 trillion tons or more of coal deposits in the United States, about 256 billion tons of it recoverable with current mining technologies.

A U.S. ton equals 2,000 pounds, which is the weight of the average adult male polar bear. So imagine how much space nearly 4 trillion polar bears would take up. That’s how much coal may be buried beneath the ground in the U.S.

7 Billion on Federal Lands

The Bureau of Land Management oversees leases for over 7 billion tons of coal across 570 million acres of federally owned lands. Just over 40 percent of coal produced in the U.S. is mined on public lands, nearly all of it in the Powder River Basin of Montana and Wyoming.

After hitting a 21st-century peak of 1.2 billion tons in 2008, U.S. coal production hovered slightly above or below 1 billion tons until 2015. That year coal production dropped by 10 percent, to about 897 million tons. The Energy Information Agency hasn’t yet released its final analysis for 2016, but reported in January that production for the year was about 743 million tons, 17 percent lower than 2015.

66,000 Jobs

There were about 66,000 jobs in coal mining in 2015, the last year for which the Federal Energy Information Agency has finalized its analysis. It was the lowest number since the agency began tracking the data in 1978.

During the first half of the 20th century, U.S. coal mines employed hundreds of thousands of workers a year, peaking for all time at 785,000 people in 1920. That number was down to a quarter of a million by 1980, and has been falling fairly steadily since.

The “War on Coal”

A combination of forces has lowered demand for coal in the United States, among them the free market. Thanks to the advent of hydraulic fracturing technologies, there has been a strong domestic supply of cheap natural gas for the past several years. These low gas prices have undercut the price of coal, and driven several coal corporations into bankruptcy, including industry behemoths Peabody Energy and Arch Coal.

Coal fires up a third of the electricity generated in the U.S., but that’s down from nearly 50 percent in 2007. Natural gas passed both coal and nuclear’s grid share to generate over a third of the nation’s electrical power in 2016.

The gas glut coincided with strengthened Clean Air Act regulations aimed at slashing many dangerous pollutants caused by burning coal, such as mercury, heavy metals, and sulfur dioxide. That gave electricity suppliers another incentive to transition to cleaner-burning gas.

Renewables are also becoming competitive with coal. As concerns about the public health, environmental, and climate costs of coal-fired electricity have grown, 29 states, along with many municipalities, have adopted renewable energy portfolio standards, compelling utilities to increase use of solar, wind, and other non-fossil-fuel energy sources. Wind power’s growth has been particularly striking: From barely measurable a decade ago to 6 percent of the national electricity mix in 2016, when the sector employed 102,000 workers — a 32 percent jump from the year before.

The Legacy of the Louisiana Purchase

Today’s public lands system took root during the first few decades of U.S. history with two key developments. First, states that originated from the original 13 colonies gave up their territorial claims to lands between the Allegheny Mountains and the Mississippi River to the federal government. Then, in 1803, France sold a vast swath of territory in the center of the continent to the U.S. in the Louisiana Purchase. Together, these acquisitions gave the federal government ownership of what we eventually learned were coal-rich lands in Appalachia, as well as the Powder River Basin of eastern Wyoming and Montana.

Fast-forward across the next two centuries of American history, and we arrive at 2017, where the feds still own a great deal of that land outright, and in other areas kept ownership of the minerals beneath while transferring ownership of the surface — a property rights situation called the “split estate.”

The Coal Leasing Moratorium on Federal Lands

In early 2016 the Obama administration put auctions for federal coal leases on hold, so that it could review the program’s costs, returns to taxpayers, and impacts on the environment.

The federal coal leasing program was first created in 1920 and has been largely unchanged since the Reagan era. While the program has returned about $10 billion to federal and state coffers in the past 10 years, both federal government and independent analyses have found that taxpayers are losing tens of billions more to its outdated royalty rate (which is a third lower than the rate companies pay for offshore oil and gas drilling) and uncompetitive bidding process.

The Obama administration’s review of the program, released in January, recommended increasing the royalty rate, as well as ways to begin factoring the costs of climate impacts into the program, and identified areas where more review was needed to modernize the program.

Along with ending the leasing moratorium, Secretary Zinke announced the creation of an advisory committee to “provide regular advice to the Secretary on the fair market value of and collection of revenues” from energy production on public lands. But he has made no commitment to increase the royalty rate for the coal leasing program.

6.28 Tons Per Miner Per Hour

Technological advances have been long making it easier to get more coal out of the ground with fewer workers. Automation has more than tripled the coal produced per miner hour in the past three decades, from 1.93 tons in 1980 to 6.28 tons in 2015, according to the Brookings Institution, a Washington, D.C.–based policy think tank. Automation “has been eating into coal jobs over a long period of time — years before concerns about climate change led to the environmental regulations that President Trump solely blames for the industry’s decline.”

Over the same time period, coal production from underground mining dropped from 41 to 35 percent, while more easily automated surface mining, in which miners blast down into coal deposits from above ground, grew six points, to 65 percent. “Coal companies in the Powder River Basin in Montana and Wyoming,” where surface mining is standard, “can extract more than 11 times as much coal per employee hour as coal companies in the Appalachian Basin,” according to Brookings.

Automation, combined with cheaper natural gas, competitively priced renewable energy technologies, and stronger curbs on harmful air pollution, mean that while the number of jobs in coal mining may tick up or down from year to year, it’s unlikely that there will be major job growth in the industry — even under a White House that wants to wish away the realities of climate change and gut environmental protections.